We propose to use the analysis of excitation-emission matrices (EEMs) of endogenous laser-induced fluorescence (LIF) obtained in vivo for the diagnosis of premalignancies in the colon and the esophagus. We will develop a technique to analyze fluorescence emission spectra in the 350-700 nm range, excited from 337 to 610 nm, and to obtain information about the chemical and structural composition of the tissue type under investigation. Our goal is to find spectroscopic signatures for normal tissue, hyperplastic and adenomatous polyps in the case of the colon and for normal and Barrett's epithelium, low and high grade dysplasia in the case of the esophagus. Initially, we will perform microscpectrofluorometry studies with specimens from the different tissue types to associate excitation-emission spectra to particular fluorescing tissue components (Aim 1). This information will be used for the development of algorithms that are designed to analyze EEMs acquired in vivo (Aim 2). We will seek spectroscopic signatures over a wide range excitation wavelengths that distinguish the different tissue types with higher sensitivity than current in vivo LIF procedures performed usually at a single excitation wavelength. The minimum number of spectroscopic features required to characterize each tissue type will be used for the design of fast algorithms for in vivo diagnosis of premalignancy. In Aim 3, we will implement technical improvements on the current fast-EEM acquisition system to maximize its efficiency based on results from Aim 2. The algorithms developed in Aim 2 will be validated by analyzing EEMs obtained with the improved fast-EEM system (Aim 4).